The present invention generally applies to wireless communication systems, and particularly applies to allocating time to mobile stations for the performance of processing tasks at the mobile stations.
As mobile communication devices continue their move toward complete integration into the framework of our daily lives, their range of uses continues expanding. For example, location-based services represent one area of rapidly increasing activity. In its broadest sense, the notion of location-dependent services entails tracking or otherwise identifying the locations of one or more users, perhaps at specific times, and making location-specific information available to them.
Such services might operate as “push” facilities where information is automatically delivered to a user's mobile communication device upon entering a given geographic zone or area, or might operate as “pull” services where the user solicits location-specific information from the supporting network. In either instance, the user generally gives prior approval for the use of his or her mobile communication device in location-based services. Emergency services location operations generally represent an exception to this prior approval scheme.
In any case, a given wireless communication network might offer a range of different location-based services, perhaps available based on varying subscription costs. Further flexibility is gained by giving third-party location services providers controlled access to the wireless communication network. In this manner, entities other than the network service provider can offer network subscribers selected location-based services, often doing so based on formal agreements between the third-party provider, the network operator, and the individual subscribers.
Effective, accurate, and timely location measurement entails overcoming many challenges. Different types of wireless networks use differing mobile positioning schemes. Positioning schemes range from the relatively course approach wherein a mobile's position is reported only to the “serving cell,” to more sophisticated approaches based on Global Positioning System (GPS) information, which can yield mobile station position accuracy on the order of ten meters. Even without GPS, wireless networks using time-of-arrival techniques provide measurement accuracies of one hundred meters or less.
In general, the various wireless network implementations each support several approaches to mobile station positioning. For example, the technical specification TS 43.059 specifies standard LoCation Services (LCS) methods for networks based on the GSM-EDGE Radio Access Network (GERAN) standards, where GSM represents Global System for Mobile Communication, and EDGE represents Enhanced Data Rates through Global Evolution. As those skilled in the art will recognize, EDGE specifies relatively sophisticated modulation techniques that may be used for higher data rate communication within the radio frequency spectrum allocated for GSM systems. GERAN systems can employ cell coverage based positioning methods, Enhanced Observed Time Difference (E-OTD) positioning methods, and/or GPS based positioning methods.
Similarly, the developing standards falling under the umbrella of Universal Terrestrial Radio Access Network (UTRAN) allow for various positioning approaches. The technical specification TS 25.305 UTRAN Stage 2 identifies supported locating methods as including cell coverage based positioning methods, Observed Time Difference of Arrival (OTDOA) positioning methods, and GPS based positioning methods.
Common to many of these schemes, and true across these and other network types, most positioning approaches depend on the individual mobile stations to support at least some of the position-related operations necessary to locate the mobile station to the desired accuracy within the wireless network. That is, most positioning approaches require the mobile station to perform at least some of the measurements and/or computations associated with location determination.
This reliance on the mobile station taxes its ability to, in some cases, compute and provide timely position-related information. For example, General Packet Radio Service (GPRS) in GERAN provides relatively high-speed packet data services to GPRS-capable mobile stations. The maximum data rate depends on a number of parameters, including the capabilities of the mobile station itself. In general, however, the higher the data rate, the less “free” time available to the mobile station. That is, under packet data service operation, the mobile station's time is increasingly dedicated to transmit and/or receive operations with increasing data rate.
Indeed, operating scenarios within the context of GPRS and other network types can arise where the mobile station is engaged in data communication services to the extent that it lacks enough free processing time to perform required position-related operations. Ideally, the wireless communication network would include provisions that, where appropriate, allocate the time needed by the mobile station for position-related operations without disrupting ongoing communication.